Messages in this thread | | | Date | Fri, 2 Apr 2010 12:02:05 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [patch] oom: give current access to memory reserves if it has been killed |
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On Fri, 2 Apr 2010, Oleg Nesterov wrote:
> > > Yes, you are right. OK, oom_badness() can never return points < 0, > > > we can make it int and oom_badness() can return -1 if !mm. IOW, > > > > > > - unsigned int points; > > > + int points; > > > ... > > > > > > points = oom_badness(...); > > > if (points >= 0 && (points > *ppoints || !chosen)) > > > chosen = p; > > > > > > > oom_badness() and its predecessor badness() in mainline never return > > negative scores, so I don't see the value in doing this; just filter the > > task in select_bad_process() with !p->mm as it has always been done. > > David, you continue to ignore my arguments ;) select_bad_process() > must not filter out the tasks with ->mm == NULL. > > Once again: > > void *memory_hog_thread(void *arg) > { > for (;;) > malloc(A_LOT); > } > > int main(void) > { > pthread_create(memory_hog_thread, ...); > syscall(__NR_exit, 0); > } > > Now, even if we fix PF_EXITING check, select_bad_process() will always > ignore this process. The group leader has ->mm == NULL. > > See? > > That is why I think we need something like find_lock_task_mm() in the > pseudo-patch I sent. >
I'm not ignoring your arguments, I think you're ignoring what I'm responding to. I prefer to keep oom_badness() to be a positive range as it always has been (and /proc/pid/oom_score has always used an unsigned qualifier), so I disagree that we need to change oom_badness() to return anything other than 0 for such tasks. We need to filter them explicitly in select_bad_process() instead, so please do this there.
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